Rotation detection device and cable with sensor

ABSTRACT

A rotation detection device includes a detected member that is mounted to a rotating member and has a plurality of magnetic poles arranged in a circumferential direction about a rotational axis of the rotating member, and a sensor section that is mounted to a stationary member not rotating with rotation of the rotating member and is arranged to face the detected member. The sensor section includes plural magnetic sensors each including a plate-shaped detection section that includes a magnetism detection element for detecting a magnetic field from the detected member, a signal processing circuit for processing a signal output from the magnetism detection element, and a cover collectively covering the magnetism detection element and the signal processing circuit, and wherein the detection sections are stacked in a direction along which the sensor section and the detected member face each other.

TECHNICAL FIELD

The present invention relates to a rotation detection device and a cablewith sensor.

BACKGROUND ART

A rotation detection device used on a bearing unit of a wheel to detecta rotational speed of a rotating member rotating with the wheel is known(see, e.g., JP 2013/47636 A).

JP 2013/47636 A discloses a rotation detection device provided with adetected member which is attached to a rotating member and has pluralmagnetic poles along a circumferential direction of the rotating member,and a magnetic sensor which is attached to a stationary member rotatablysupporting the rotating member and has a detection element for detectinga magnetic field of the detected member.

CITATION LIST Patent Literature

JP 2013/47636 A

SUMMARY OF INVENTION Technical Problem

Rotation detection devices for measuring a rotational speed of a wheelare desired to have plural magnetic sensors so that the rotational speedof wheel can be detected even in case of failure, etc., of a certainmagnetic sensor or so that the rotational speed of wheel can be detectedmore accurately.

When mounting plural magnetic sensors on a sensor section, the size ofthe entire sensor section is increased and this may cause a problemthat, e.g., it is not possible to insert the sensor section into asensor section-holding hole. Therefore, there is a demand for a sensorsection which can keep a small size even when mounting plural magneticsensors.

It is an object of the invention to provide a rotation detection deviceand a cable with sensor in which a sensor section can have a small sizewhile having plural magnetic sensors.

Solution to Problem

To solve the above-mentioned problem, a rotation detection device in anaspect of the invention is provided with a detected member that ismounted to a rotating member and has a plurality of magnetic polesarranged in a circumferential direction about a rotational axis of therotating member; and a sensor section that is mounted to a stationarymember not rotating with rotation of the rotating member and is arrangedto face the detected member, wherein the sensor section comprises aplurality of magnetic sensors each comprising a plate-shaped detectionsection that comprises a magnetism detection element for detecting amagnetic field from the detected member, a signal processing circuit forprocessing a signal output from the magnetism detection element, and acover collectively covering the magnetism detection element and thesignal processing circuit, the detection sections are stacked in adirection along which the sensor section and the detected member faceeach other, and the magnetic sensor arranged farthest from the detectedmember has higher sensitivity than the magnetic sensor arranged closestto the detected member.

Also to solve the above-mentioned problem, a cable with sensor in anaspect of the invention is for a rotation detection device comprising adetected member that is mounted to a rotating member and has a pluralityof magnetic poles arranged in a circumferential direction about arotational axis of the rotating member, and a sensor section that ismounted to a stationary member not rotating with rotation of therotating member and is arranged to face the detected member, and thecable with sensor is provided with a cable; and the sensor sectionprovided at an end of the cable, wherein the sensor section comprises aplurality of magnetic sensors each comprising a plate-shaped detectionsection that comprises a magnetism detection element for detecting amagnetic field from the detected member, a signal processing circuit forprocessing a signal output from the magnetism detection element, and acover collectively covering the magnetism detection element and thesignal processing circuit, and the detection sections are stacked in adirection along which the sensor section and the detected member faceeach other.

Advantageous Effects of Invention

Provided according to an aspect of the invention are a rotationdetection device and a cable with sensor in which a sensor section canhave a small size while having plural magnetic sensors.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross sectional view showing a rotation detection device inan embodiment of the present invention and a vehicle wheel bearingdevice having the rotation detection device.

FIG. 2 is a perspective view showing a sensor section.

FIG. 3A is a side view showing the sensor section.

FIG. 3B is a cutaway diagram of FIG. 3A, in which a housing is shown asthe cross section.

FIG. 4A is a top view showing the sensor section.

FIG. 4B is a cutaway diagram of FIG. 4A, in which the housing is shownas the cross section.

FIG. 4C is a top view showing a magnetic sensor and electric wires.

FIG. 5A is an explanatory diagram illustrating a cable with sensor in amodification of the invention.

FIG. 5B is a cross sectional view showing the cable shown in FIG. 5A.

DESCRIPTION OF EMBODIMENTS Embodiment

An embodiment of the invention will be described below in conjunctionwith the appended drawings.

(Configuration of Wheel Bearing Device 10)

FIG. 1 is a cross sectional view showing a rotation detection device inthe present embodiment and a vehicle wheel bearing device having therotation detection device.

The wheel bearing device 10 is provided with an inner race 11 as arotating member having a cylindrical main body 110 and a flange 111 tobe attached to a wheel, an outer race 12 arranged on the outerperipheral side of the main body 110 of the inner race 11, pluralspherical rolling elements 13 arranged between a pair of racewaysurfaces 11 b, 11 b formed on an outer surface 11 a of the inner race 11and a pair of raceway surfaces 12 b, 12 b formed on an inner surface 12a of the outer race 12 and roll and move on the raceway surfaces 11 band 12 b, and a rotation detection device 1 for detecting a rotationalspeed of the inner race 11 with respect to the outer race 12 (i.e., awheel speed).

A through-hole is formed at the middle portion of the main body 110 ofthe inner race 11 along a rotational axis line O thereof and a splinefitting portion 110 a for coupling a drive shaft (not shown) is formedon an inner surface of the through-hole. The pair of raceway surfaces 11b, 11 b of the inner race 11 are formed parallel to each other andextend in a circumferential direction.

The flange 111 of the inner race 11 is provided integrally with the mainbody 110 so as to protrude radially outward of the main body 110. Theflange 111 has plural through-holes 111 a into which bolts forattachment to a wheel (not shown) are press-fitted.

The outer race 12 is formed in a cylindrical shape and is fixed, byplural bolts 91 (only one bolt 91 is shown in FIG. 1), to a knuckle 9which is coupled to a vehicle body. The knuckle 9 is an example of thestationary member which rotatably supports the inner race 11. The pairof raceway surfaces 12 b, 12 b of the outer race 12 are formed parallelto each other and extend in a circumferential direction so as to facethe pair of raceway surfaces 11 b, 11 b of the inner race 11. At an endof the outer race 12 on the side where the flange 111 of the inner race11 is located, a sealing 14 is arranged between the inner race 11 andthe outer race 12.

A holding hole 90 for holding a sensor section 3 of the rotationdetection device 1 (described next) is formed on the knuckle 9. Theholding hole 90 has a circular shape in the cross section perpendicularto the central axis thereof and penetrates the knuckle 9 in a radialdirection from the rotational axis line O.

(Rotation Detection Device 1)

FIG. 2 is a perspective view showing a sensor section. FIG. 3A is a sideview showing the sensor section and FIG. 3B is a cutaway diagram thereofin which a housing is shown as the cross section. FIG. 4A is a top viewshowing the sensor section, FIG. 4B is a cutaway diagram thereof inwhich the housing is shown as the cross section, and FIG. 4C is a topview showing a magnetic sensor and electric wires.

As shown in FIGS. 1 to 4, the rotation detection device 1 is providedwith a magnetic encoder 2 as a detected member which is mounted to theinner race 11 as a rotating member and has plural magnetic poles (notshown) arranged in a circumferential direction about a rotational axis(the rotational axis line O) of the inner race 11, and a sensor section3 which is mounted to the knuckle 9 as a stationary member not rotatingwith rotation of the inner race 11 and is arranged to face the magneticencoder 2.

The magnetic encoder 2 is formed in an annular shape having a thicknessin a direction parallel to the rotational axis line O. The magneticencoder 2 is supported by a support member 112 fixed to the outersurface 11 a of the inner race 11 and is attached so as to rotatetogether with the inner race 11. In addition, the magnetic encoder 2 hasN-poles and S-poles which face the sensor section 3 and are alternatelyarranged along the circumferential direction.

The sensor section 3 is provided at an end of a cable 4. The cable 4having the sensor section 3 at an end is a cable with sensor 100 in thepresent embodiment. In the present embodiment, the magnetic encoder 2and a tip of the sensor section 3 face each other in an axial directionparallel to the rotational axis line O.

In the rotation detection device 1 of the present embodiment, the sensorsection 3 has plural magnetic sensors 30 and a housing portion 31 whichis formed of a resin mold collectively covering the plural magneticsensors 30. In this example, the sensor section 3 having two magneticsensors 30 will be described.

The cable 4 has plural pairs (two pairs in this example) of electricwires 41 corresponding to the plural magnetic sensors 30. Each electricwire 41 has a center conductor 41 a constructed from a strandedconductor formed by twisting highly conductive strands of copper, etc.,and an insulation 41 b formed of an insulating resin such ascross-linked polyethylene and covering the outer surface of the centerconductor 41 a. The cable 4 also has a sheath 42 collectively coveringtwo pairs of electric wires 41 (four electric wires 41).

The two pairs of electric wires 41 are exposed from the sheath 42 at anend of the cable 4, and the center conductors 41 a are further exposedfrom the insulations 41 b at an end of the electric wires 41. The centerconductor 41 a exposed from the insulation 41 b is electricallyconnected to a connection terminal 301 of the corresponding magneticsensor 30 by resistance welding.

The magnetic sensor 30 has a detection section 300 and a pair ofconnection terminals 301 extending out of the detection section 300.

The detection section 300 has a magnetism detection element (not shown)for detecting a magnetic field from the magnetic encoder 2, a signalprocessing circuit (not shown) for processing a signal output from themagnetism detection element, and a resin mold 300 a as a covercollectively covering the magnetism detection element and the signalprocessing circuit. The detection section 300 is formed in asubstantially rectangular plate shape (a rectangular shape in which oneof four corners is chamfered) in a plan view. The detection axis of themagnetism detection element (a magnetic field detecting direction) isthe vertical direction in FIG. 4A (a direction of a tangent to a circlehaving a center on the rotational axis line O).

The pair of connection terminals 301 extend from one long side of thedetection section 300 (a long side not connected to the chamferedcorner) in a direction perpendicular to the long side, and the twoconnection terminals 301 are formed parallel to each other. In thepresent embodiment, the both connection terminals 301 are formed in astrip shape and tips thereof are electrically connected to the centerconductors 41 a of the corresponding electric wires 41.

The pair of connection terminals 301 of one magnetic sensor 30 locatedcloser to the magnetic encoder 2 (the magnetic sensor 30 located on thelower side in the example shown in FIG. 3B) extend linearly and parallelto each other in the same direction that the center conductors 41 aextend. On the other hand, the pair of connection terminals 301 of theother magnetic sensor 30 located farther from the magnetic encoder 2(the magnetic sensor 30 located on the upper side in the example shownin FIG. 3B) are bent into a crank shape. In detail, the pair ofconnection terminals 301 of the other magnetic sensor 30 has a portionextending horizontally from a joint with the center conductors 41 a inthe same direction that the center conductors 41 a extend, a portionbent from the horizontal potion and extending toward the one magneticsensor 30 (obliquely downward left in the example shown in FIG. 3B), anda portion bent from the oblique portion and extending horizontally inthe same direction that the center conductors 41 a extend.

Although it is not shown in the drawings, a capacitative element forsuppressing noise is connected between the two connection terminals 301,and a capacitative element protecting portion 302 formed of a resin moldis provided to cover the capacitative element and a portion of theconnection terminals 301 connected to the capacitative element. Thecapacitative element protecting portion 302 provided on the othermagnetic sensor 30 is arranged between the pair of connection terminals301 of the one magnetic sensor 30 and the pair of the connectionterminals 301 of the other magnetic sensor 30 by effectively using aspace formed between the pair of linear connection terminals 301 and thepair of crank-shaped connection terminals 301.

In the rotation detection device 1 of the present embodiment, thedetection sections 300 of plural (two in this example) magnetic sensors30 are stacked in a direction along which the sensor section 3 and themagnetic encoder 2 face each other. Also, the detection sections 30 arestacked in a direction intersecting (orthogonal in the presentembodiment) with a lead-out direction along which the cable 4 is led outof the housing portion 31. In addition, in the present embodiment, themagnetic sensor 30 arranged farthest from the magnetic encoder 2 hashigher sensitivity than the magnetic sensor 30 arranged closest to themagnetic encoder 2. When the cable 4 is bent and an L-shaped housingportion 30 is formed by molding a resin with the bent portion of thecable 4, the detection sections 30 are stacked in the same direction asthe lead-out direction along which the cable 4 is led out of the housingportion 31.

The detection sections 300 of the two magnetic sensors 30 are stacked ina thickness direction thereof. That is, in the present embodiment, thedirection along which the sensor section 3 and the magnetic encoder 2face each other coincides with the thickness direction (stackingdirection) of the detection sections 300. The direction along which thesensor section 3 and the magnetic encoder 2 face each other here doesnot need to exactly coincide with the thickness direction (stackingdirection) of the detection sections 300, and may be slightly off. Inother words, “the detection sections 300 are stacked in a directionalong which the sensor section 3 and the magnetic encoder 2 face eachother” includes the case where the direction along which the sensorsection 3 and the magnetic encoder 2 face each other is several degrees(e.g., ±10°) off the stacking direction of the detection sections 300.

In the present embodiment, since the magnetic encoder 2 and the tip ofthe sensor section 3 face each other in the axial direction parallel tothe rotational axis line O, the thickness direction (stacking direction)of the detection sections 300 coincides with the axial direction.However, it is not limited thereto. For example, when the magneticencoder 2 and the tip of the sensor section 3 face each other in aradial direction which is perpendicular to the rotational axis line O,the thickness direction (stacking direction) of the detection sections300 coincides with the radial direction.

In addition, in the present embodiment, the two detection sections 300are stacked directly. In other words, a surface of one detection section300 is in contact with a surface of the other detection section 300.Thus, the size can be smaller and a distance between the magnetismdetection elements of the two detection sections 300 can be maintainedconstant more easily than when the two detection sections 300 arearranged at a distance, and in addition to this, detection accuracy canbe improved since a distance between the magnetic encoder 2 and themagnetic sensor 30 arranged farther from the magnetic encoder 2 isminimized. In the present embodiment, the two detection sections 300 arenot bonded/fixed by an adhesive, etc., and the two detection sections300 in a stacked state are housed in the housing portion 31.

In addition, the two detection sections 300 are desirably stacked sothat the two magnetism detection elements at least partially overlap inthe direction along which the sensor section 3 and the magnetic encoder2 face each other (in the axial direction).

Even when one magnetic sensor 30 fails, it is possible to continuedetection by other magnetic sensor(s) 30 since plural magnetic sensors30 are used, and reliability of the rotation detection device 1 isthereby improved.

In addition, by stacking the detection sections 300 (stacking in thethickness direction), it is possible to compactly arrange the pluralmagnetic sensors 30 as compared to when, e.g., the sensor section 3 arearranged side by side in a width direction which is perpendicular to thethickness direction. Therefore, the size of the entire sensor section 3can be kept small even when using plural magnetic sensors 30.

The thickness of the detection section 300 is, e.g., about 1 mm.However, when the detection sections 300 of the two magnetic sensors 30are arranged at a distance for some reasons or when a distance (gap)between the sensor section 3 and the magnetic encoder 2 is relativelylarge, magnetic field strength detected by the magnetic sensor 30located far from the magnetic encoder 2 could become small, causing adecrease in detection accuracy.

Based on this, in the present embodiment, sensitivity of the magneticsensor 30 arranged farthest from the magnetic encoder 2 is higher thansensitivity of the magnetic sensor 30 arranged closest to the magneticencoder 2. When using two magnetic sensors 30 as it is in the presentembodiment, a magnetic sensor having higher sensitivity than themagnetic sensor 30 arranged on the magnetic encoder 2 side is used asthe magnetic sensor 30 arranged on the side opposite to the magneticencoder 2.

“Higher sensitivity” here means being capable of detecting a smallermagnetic field strength. In other words, “higher sensitivity” means thatminimum value of detectable magnetic field strength is smaller.

In the present embodiment, a Hall IC is used as the magnetic sensor 30arranged on the magnetic encoder 2 side, and a GMR (Giant MagnetoResistive effect) sensor having a higher sensitivity than the Hall IC isused as the magnetic sensor 30 arranged on the side opposite to themagnetic encoder 2. When using the Hall IC as the magnetic sensor 30arranged on the magnetic encoder 2 side, an AMR (Anisotropic MagnetoRestive) sensor or a TMR (Tunneling Magneto Resistive) sensor may bealternatively used as the magnetic sensor 30 arranged on the sideopposite to the magnetic encoder 2.

In addition, when more accurate detection of a rotational speed of theinner race 11 with respect to the outer race 12 (a wheel speed) isrequired, such as when, e.g., detection result of the rotational speedof the inner race 11 with respect to the outer race 12 (the wheel speed)is supposed to be used for a vehicle body stability control system or anindirect air pressure detection device, a GMR sensor or an AMR sensormay be used as the magnetic sensor 30 arranged on the magnetic encoder 2side, while using a TMR sensor having a higher sensitivity than the GMRsensor or AMR sensor as the magnetic sensor 30 arranged on the sideopposite to the magnetic encoder 2. Alternatively, it is also possibleto use the same type of magnetic sensors 30 having differentsensitivities in such a manner that, e.g., a GMR sensor is used as themagnetic sensor 30 arranged on the magnetic encoder 2 side, and anotherGMR sensor having a higher sensitivity than the GMR sensor arranged onthe magnetic encoder 2 side is used as the magnetic sensor 30 arrangedon the side opposite to the magnetic encoder 2. The indirect airpressure detection device here is a device which compares rotationalspeeds of four wheels (wheel speeds) of a vehicle and thereby detectsblowout, etc., occurred on a given wheel.

When using not less than three magnetic sensors 30, sensitivity ishigher in the magnetic sensor 30 located farther from the magneticencoder 2. In more detail, the magnetic sensors 30 other than themagnetic sensor 30 arranged closest to the magnetic encoder 2 havesensitivity equal to or greater than the magnetic sensor(s) 30 locatedcloser to the magnetic encoder 2. That is, when using, e.g., fourmagnetic sensors 30, it is possible to use Hall ICs having the samesensitivity as two magnetic sensors 30 arranged closer to the magneticencoder 2, and GMR sensors having the same sensitivity as two magneticsensors 30 arranged farther from the magnetic encoder 2.

The housing portion 31 integrally has a substantially cylindrical mainbody 310 collectively covering the magnetic sensor 30 and an end of thecable 4, and a flange 311 for fixing the sensor section 3 to the knuckle9. A bolt hole 312 for inserting a bolt 92 (see FIG. 1) used to fix thesensor section 3 to the knuckle 9 is formed on the flange 311, and ametal collar 313 for preventing deformation of the flange 311 due tobolt fixation is provided at the bolt hole 312 along the inner surfaceof the bolt hole 312.

A facing surface 314 which faces the magnetic encoder 2 is formed at atip portion (an end portion opposite to the side where the cable 4extends out) of the main body 310 of the housing portion 31. The sensorsection 3 is fixed to the knuckle 9 in a state that the facing surface314 faces the magnetic encoder 2 (facing in the axial direction parallelto the rotational axis line O).

It is possible to use the housing portion 31 formed of, e.g., PA(polyamide) 612 grade, Nylon 66 (Nylon is a registered trademark), orPBT (polybutylene terephthalate), etc. In the present embodiment, PA 612mixed with glass filler is used as a resin for forming the housingportion 31.

(Modification of Cable with Sensor 100)

Although the cable 4 in the embodiment is formed by collectivelycovering two pairs of electric wires 41 with the sheath 42, it is notlimited thereto. The cable 4 may contain electric wires other than theelectric wires 41 for the sensor section 3.

In a cable with sensor 100 a shown in FIGS. 5A and 5B, a cable 4 a isprovided with two twisted-pair wires 43 each formed by twisting a pairof electric wires 41, a pair of power wires 7 having larger outerdiameter and conductor cross-sectional area than the electric wire 41, atape member 45 spirally wound around an assembled article 44 which isformed by twisting the twisted-pair wires 43 and the power wires 7together, and a sheath 42 covering the outer surface of the tape member45.

The sensor section 3 is provided at one end of the two twisted-pairwires 43. A vehicle body-side sensor connector 75 for connection to awire group inside a junction box provided on a body of a vehicle isattached to the other end of the two twisted-pair wires 43.

In the present embodiment, the power wires 7 are used for supplying adrive current to a motor (not shown) for an electric parking brake(hereinafter, referred to as “EPB”) mounted on a wheel of the vehicle.

EPB is an electric brake system configured to output a drive current tothe motor for a predetermined period of time (e.g., for 1 second) when aparking brake activation switch is turned from an OFF state to an ONstate during the stationary state of the vehicle so that brake pads arepressed against a disc rotor of the wheel and a braking force to beapplied to the wheel is generated. The EPB is also configured to outputa drive current to the motor when the parking brake activation switch isturned from the ON state to the OFF state or when an accelerator pedalis depressed so that the brake pads move away from the disc rotor of thewheel and the braking force on the wheel is released. In other words, itis configured that an operating state of the EPB is maintained from whenthe parking brake activation switch is turned on to when the parkingbrake activation switch is turned off or the accelerator pedal isdepressed.

The power wire 7 has a power wire center conductor 71 and a power wireinsulation 72 covering the power wire center conductor 71. The powerwire center conductor 71 is constructed from a stranded conductor formedby twisting highly conductive strands of copper, etc., and the powerwire insulation 72 is formed of an insulating resin such as cross-linkedpolyethylene.

A wheel-side power connector 73 a for connection to the EPB motor isattached to one end of the pair of power wires 7, and a vehiclebody-side power connector 73 b for connection to the wire group insidethe junction box is attached to the other end of the pair of power wires7.

The assembled article 44 is formed by twisting the two twisted-pairwires 43 and the pair of power wires 7. In the present embodiment, thepower wires 7 are arranged between the two twisted-pair wires 43 in thecircumferential direction. In the cross section shown in FIG. 5A, one ofthe twisted-pair wires 43, one of the power wires 7, the othertwisted-pair wire 43 and the other power wire 7 are arranged clockwisein this order.

When the power wires 7 are arranged adjacent to each other in thecircumferential direction (when the two twisted-pair wires 43 arearranged adjacent to each other), the center of gravity of the assembledarticle 44 largely shifts from the center position of the assembledarticle 44, and the assembled article 44 formed by twisting the twotwisted-pair wires 43 and the power wires 7 in such a state is entirelydistorted. In this case, it is difficult to manufacture a straight cable4 a and there is also a problem that the cable is not flexible in somedirections at some portions in a longitudinal direction, resulting in adecrease in flexibility. By alternately arranging the twisted-pair wires43 and the power wires 7 in the circumferential direction as in thepresent embodiment, it is possible to easily realize the straight cable4 a and also to suppress a decrease in flexibility since a defect suchas non-flexibility in some directions at some portions in thelongitudinal direction is prevented from occurring.

In the EPB, a drive current is supplied to the motor basically when thevehicle is stationary. On the other hand, the rotation detection device1 is used when the vehicle is in motion and the rotation detectiondevice 1 is not used during when the drive current is supplied throughthe power wires 7. Therefore, in the present embodiment, a shieldconductor around the power wires 7 or the twisted-pair wires 43 isomitted. Omitting the shield conductor allows the cable 4 a to have asmaller outer diameter than when providing the shield conductor and alsoreduces the number of components, thereby reducing the cost.

In addition, in present embodiment, the two twisted-pair wires 43, whichtransmit an electrical signal during when the vehicle is in motion, areseparated by the pair of power wires 7 which supply a drive current tothe motor mainly after the vehicle is stopped. This can reduce crosstalkbetween the two twisted-pair wire 43 even when shield conductors aroundthe twisted-pair wires 43 are omitted.

Plural thread-like (fibrous) fillers extending in the longitudinaldirection of the cable 4 a may be arranged between the twisted-pairwires 43/the power wires 7 and the tape member 45. In this case, theassembled article 44 is formed by twisting the fillers together with thetwisted-pair wires 43 and the power wires 7. Thus, a cross sectionalshape after winding the tape member 45 around the assembled article 44can be closer to a circle. As the filler, it is possible to use afibrous material such as polypropylene yarn, staple fiber yarn (rayonstaple fiber), aramid fiber, nylon fiber or fiber plastic, a paper or acotton yarn.

The tape member 45 is spirally wound around the assembled article 44.The tape member 45 is in contact with all electric wires (four electricwires 41 and a pair of power wires 7) covered with the tape member 45.The tape member 45 is interposed between the assembled article 44 andthe sheath 42 and serves to reduce friction between the assembledarticle 44 (the electric wires 41 and the power wires 7) and the sheath42 when being bent. In other words, providing the tape member 45 canreduce friction between the electric wires 41/the power wires 7 and thesheath 42 without a lubricant such as talc powder, and thus reducesstress applied to the electric wires 41 and the power wires 7 when beingbent, and it is thereby possible to improve flex resistance.

It is desirable to use the tape member 45 which is slidable (has a lowfriction coefficient) with respect to the insulation 41 b of theelectric wire 41 or the power wire insulation 72 of the power wire 7,and it is possible to use the tape member 45 formed of, e.g., anon-woven fabric, paper, or resin (resin film, etc.). The tape member 45is spirally wound around the assembled article 44 so as to overlap at aportion in a width direction (a direction perpendicular to thelongitudinal direction and thickness direction of the tape member 45).The overlapping portion of the tape member 45 is not adhered by anadhesive, etc.

(Functions and Effects of the Embodiment)

As described above, in the rotation detection device 1 of the presentembodiment, the sensor section 3 is provided with plural magneticsensors 30 each of which has the plate-shaped detection section 300having a magnetism detection element for detecting a magnetic field fromthe magnetic encoder 2, a signal processing circuit for processing asignal output from the magnetism detection element, and the resin mold300 a collectively covering the magnetism detection element and thesignal processing circuit, and the detection sections 300 are stacked ina direction along which the sensor section 3 and the magnetic encoder 2face each other.

Due to this configuration, the sensor section 3 can have a small sizeeven when plural magnetic sensors 30 are used to provide redundancy orto improve detection accuracy. In addition, even when, e.g., a gapbetween the sensor section 3 and the magnetic encoder 2 is large or astacking interval of the detection sections 300 is large, it is possibleto perform detection using plural magnetic sensors 30.

In addition, in the present embodiment, the magnetic sensor 30 arrangedfarthest from the magnetic encoder 2 has higher sensitivity than themagnetic sensor 30 arranged closest to the magnetic encoder 2. Whenusing two magnetic sensors 30, for example, sensors having sufficientlyhigh sensitivity could be use for the both magnetic sensors 30. In thiscase, however, the cost of the rotation detection device 1 is increasedsince the magnetic sensor 30 having high sensitivity is expensive.According to the present embodiment, a highly reliable rotationdetection device 1 using plural magnetic sensors 30 can be realizedwhile reducing the cost.

(Summary of the Embodiments)

Technical ideas understood from the embodiment will be described belowciting the reference numerals, etc., used for the embodiment. However,each reference numeral, etc., described below is not intended to limitthe constituent elements in the claims to the members, etc.,specifically described in the embodiment.

[1] A rotation detection device (1), comprising: a detected member (2)that is mounted to a rotating member (11) and has a plurality ofmagnetic poles arranged in a circumferential direction about arotational axis of the rotating member (11); and a sensor section (3)that is mounted to a stationary member (9) not rotating with rotation ofthe rotating member (11) and is arranged to face the detected member(2), wherein the sensor section (3) comprises a plurality of magneticsensors (30) each comprising a plate-shaped detection section (300) thatcomprises a magnetism detection element for detecting a magnetic fieldfrom the detected member (2), a signal processing circuit for processinga signal output from the magnetism detection element, and a cover (300a) collectively covering the magnetism detection element and the signalprocessing circuit, and the detection sections (300) are stacked in adirection along which the sensor section (3) and the detected member (2)face each other.

[2] The rotation detection device (1) defined by [1], wherein themagnetic sensor (30) arranged farthest from the detected member (2) hashigher sensitivity than the magnetic sensor (30) arranged closest to thedetected member (2).

[3] The rotation detection device (1) defined by [2], wherein the sensorsection (3) comprises the two magnetic sensors (30), the magnetic sensor(30) arranged on a side closer to the detected member (2) comprises aHall IC, and the magnetic sensor (30) arranged on the side opposite tothe detected member (2) comprises a GMR sensor, an AMR sensor or a TMRsensor.

[4] The rotation detection device (1) defined by [2], wherein the sensorsection (3) comprises the two magnetic sensors (30), the magnetic sensor(30) arranged on a side closer to the detected member (2) comprises aGMR sensor or an AMR sensor, and the magnetic sensor (30) arranged onthe side opposite to the detected member (2) comprises a TMR sensor.

[5] A cable with sensor (100) that is used for a rotation detectiondevice (1) comprising a detected member (2) that is mounted to arotating member (11) and has a plurality of magnetic poles arranged in acircumferential direction about a rotational axis of the rotating member(11), and a sensor section (3) that is mounted to a stationary member(9) not rotating with rotation of the rotating member (11) and isarranged to face the detected member (2), the cable with sensor (100)comprising: a cable (4); and the sensor section (3) provided at an endof the cable (4), wherein the sensor section (3) comprises a pluralityof magnetic sensors (30) each comprising a plate-shaped detectionsection (300) that comprises a magnetism detection element for detectinga magnetic field from the detected member (2), a signal processingcircuit for processing a signal output from the magnetism detectionelement, and a cover (300 a) collectively covering the magnetismdetection element and the signal processing circuit, and the detectionsections (300) are stacked in a direction along which the sensor section(3) and the detected member (2) face each other.

[6] The cable with sensor (100) defined by [5], wherein the magneticsensor (30) arranged farthest from the detected member (2) has highersensitivity than the magnetic sensor (30) arranged closest to thedetected member (2).

[7] The cable with sensor (100 a) defined by [5] or [6], wherein therotation detection device (1) is used to detect a rotational speed ofthe rotating member (11) that rotates with a wheel of a vehicle, and thecable (4) comprises a plurality of pairs of electric wires (41)corresponding to the plurality of magnetic sensors (30), power wires (7)for supplying a drive current to a motor for an electric parking brakemounted on the wheel, and a sheath (42) collectively covering theplurality of pairs of electric wires (41) and the power wires (7).

Although the embodiment of the invention has been described, theinvention according to claims is not to be limited to the embodimentdescribed above. Further, please note that all combinations of thefeatures described in the embodiment are not necessary to solve theproblem of the invention.

The invention can be appropriately modified and implemented withoutdeparting from the gist thereof.

For example, although the rotation detection device 1 which detects awheel speed has been described in the embodiment, it is not limitedthereto. The invention is applicable to, e.g., a drive shaft sensor or acrank angle sensor, etc.

REFERENCE SIGNS LIST

1 ROTATION DETECTION DEVICE

2 MAGNETIC ENCODER (DETECTED MEMBER)

3 SENSOR SECTION

30 MAGNETIC SENSOR

300 DETECTION SECTION

300 a RESIN MOLD (COVER)

301 CONNECTION TERMINAL

31 HOUSING PORTION

4 CABLE

9 KNUCKLE (STATIONARY MEMBER)

10 WHEEL BEARING DEVICE

11 INNER RACE (ROTATING MEMBER)

12 OUTER RACE

13 ROLLING ELEMENT

100 CABLE WITH SENSOR

1. A rotation detection device, comprising: a detected member that ismounted to a rotating member and has a plurality of magnetic polesarranged in a circumferential direction about a rotational axis of therotating member; and a sensor section that is mounted to a stationarymember not rotating with rotation of the rotating member and is arrangedto face the detected member, wherein the sensor section comprises aplurality of magnetic sensors each comprising a plate-shaped detectionsection that comprises a magnetism detection element for detecting amagnetic field from the detected member, a signal processing circuit forprocessing a signal output from the magnetism detection element, and acover collectively covering the magnetism detection element and thesignal processing circuit, and wherein the detection sections arestacked in a direction along which the sensor section and the detectedmember face each other.
 2. The rotation detection device according toclaim 1, wherein the magnetic sensor arranged farthest from the detectedmember has higher sensitivity than the magnetic sensor arranged closestto the detected member.
 3. The rotation detection device according toclaim 2, wherein the sensor section comprises the two magnetic sensors,the magnetic sensor arranged on a side closer to the detected membercomprises a Hall IC, and the magnetic sensor arranged on the sideopposite to the detected member comprises a GMR sensor, an AMR sensor ora TMR sensor.
 4. The rotation detection device according to claim 2,wherein the sensor section comprises the two magnetic sensors, themagnetic sensor arranged on a side closer to the detected membercomprises a GMR sensor or an AMR sensor, and the magnetic sensorarranged on the side opposite to the detected member comprises a TMRsensor.
 5. A cable with sensor that is used for a rotation detectiondevice comprising a detected member that is mounted to a rotating memberand has a plurality of magnetic poles arranged in a circumferentialdirection about a rotational axis of the rotating member, and a sensorsection that is mounted to a stationary member not rotating withrotation of the rotating member and is arranged to face the detectedmember, wherein the cable with sensor comprises: a cable; and the sensorsection provided at an end of the cable, wherein the sensor sectioncomprises a plurality of magnetic sensors each comprising a plate-shapeddetection section that comprises a magnetism detection element fordetecting a magnetic field from the detected member, a signal processingcircuit for processing a signal output from the magnetism detectionelement, and a cover collectively covering the magnetism detectionelement and the signal processing circuit, and wherein the detectionsections are stacked in a direction along which the sensor section andthe detected member face each other.
 6. The cable with sensor accordingto claim 5, wherein the magnetic sensor arranged farthest from thedetected member has higher sensitivity than the magnetic sensor arrangedclosest to the detected member.
 7. The cable with sensor according toclaim 5, wherein the rotation detection device is used to detect arotational speed of the rotating member that rotates with a wheel of avehicle, and the cable comprises a plurality of pairs of electric wirescorresponding to the plurality of magnetic sensors, power wires forsupplying a drive current to a motor for an electric parking brakemounted on the wheel, and a sheath collectively covering the pluralityof pairs of electric wires and the power wires.
 8. The cable with sensoraccording to claim 6, wherein the rotation detection device is used todetect a rotational speed of the rotating member that rotates with awheel of a vehicle, and the cable comprises a plurality of pairs ofelectric wires corresponding to the plurality of magnetic sensors, powerwires for supplying a drive current to a motor for an electric parkingbrake mounted on the wheel, and a sheath collectively covering theplurality of pairs of electric wires and the power wires.